
Industrial Ethernet Networks
2-5
SIMATIC NET Twisted-Pair and Fiber-Optic Networks
C79000-G8976-C125-02
2.2 Industrial Ethernet
Industrial Twisted Pair (10BASE-T)
Industrial Twisted Pair is based on the Twisted-Pair standard IEEE 802.3i
(10BASE-T) /3/ and operates at a transmission rate of 10 Mbps.
The transmission medium is a shielded cable with two twisted pairs with a
characteristic impedance of 100 ohms. It is terminated according to the 10BASE-T
standard with RJ-45 connectors. As an alternative, sub-D connectors are also
available in the SIMATIC NET product range.
Twisted pair connections are always end-to-end connections between two
electrically active components. This means that there is always a direct link from
one DTE to a port of a network component. The network component is responsible
for regenerating received signals and distributing them by outputting the data again
to all output ports. In the SIMATIC NET Industrial Ethernet network, these tasks
are handled by the OLM, ELM, OSM, and ESM network components. The
maximum length of the link between a DTE and network component (known as the
link segment) must not exceed 100 m.
Fiber Optic (10BASE-FL)
The fiber-optic variant for the 10 Mbps transmission rate in Industrial Ethernet is
based on the IEEE 802.3i standard (10BASE-FL) /4/.
The transmission medium is a multimode fiber-optic cable with glass fibers of the
type 62.5/125 µm or 50/125 µm.
Fiber-optic links are always end-to-end links between two active components. This
means that there is always a direct link between a network component and a port
of another network component. One network component is responsible for
regenerating received signals and distributing them by outputting the data again to
output ports. In SIMATIC NET Industrial Ethernet networks, this task is handled by
the OLM network component.
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